Merge pull request #1319 from saidst/feature/extend-azure-private-dns-tutorial

Reworked tutorial for Azure Private DNS

docs/tutorials/azure-private-dns.md

@@ -1,20 +1,60 @@
-
 # Set up ExternalDNS for Azure Private DNS
 
 This tutorial describes how to set up ExternalDNS for managing records in Azure Private DNS.  
-It assumes to deploy ExternalDNS as a container Kubernetes.
-
 
 It comprises of the following steps:
-1) Provision Azure Private DNS
+1) Install NGINX Ingress Controller 
-2) Configure service principal for managing the zone
+2) Provision Azure Private DNS
-3) Deploy ExternalDNS  
+3) Configure service principal for managing the zone
+4) Deploy ExternalDNS  
+
+Everything will be deployed on Kubernetes.   
+Therefore, please see the subsequent prerequisites.
 
 ## Prerequisites
-- Azure Kubernetes Service available
+- Azure Kubernetes Service is deployed and ready
-- nginx-ingress-controller incl. `--publish-service=namespace/nginx-ingress-controller-svcname` available
 - [Azure CLI 2.0](https://docs.microsoft.com/en-us/cli/azure/install-azure-cli) and `kubectl` installed on the box to execute the subsequent steps 
 
+## Install NGINX Ingress Controller 
+
+Helm is used to deploy the ingress controller. 
+
+We employ the popular chart [stable/nginx-ingress](https://github.com/helm/charts/tree/master/stable/nginx-ingress).
+
+```
+$ helm install stable/nginx-ingress \
+     --name nginx-ingress \
+     --set controller.publishService.enabled=true
+```
+  
+The parameter `controller.publishService.enabled` needs to be set to `true.`  
+
+It will make the ingress controller update the endpoint records of ingress-resources to contain the external-ip of the loadbalancer serving the ingress-controller. 
+This is crucial as ExternalDNS reads those endpoints records when creating DNS-Records from ingress-resources.  
+In the subsequent parameter we will make use of this. If you don't want to work with ingress-resources in your later use, you can leave the parameter out.
+
+Verify the correct propagation of the loadbalancer's ip by listing the ingresses.
+```
+$ kubectl get ingress
+```
+The address column should contain the ip for each ingress. ExternalDNS will pick up exactly this piece of information.
+```
+NAME     HOSTS             ADDRESS          PORTS   AGE
+nginx1   sample1.aks.com   52.167.195.110   80      6d22h
+nginx2   sample2.aks.com   52.167.195.110   80      6d21h
+```
+
+
+If you do not want to deploy the ingress controller with Helm, ensure to pass the following cmdline-flags to it through the mechanism of your choice:
+
+```
+flags:
+--publish-service=<namespace of ingress-controller >/<svcname of ingress-controller>
+--update-status=true (default-value)
+
+example:
+./nginx-ingress-controller --publish-service=default/nginx-ingress-controller
+``` 
 
 ## Provision Azure Private DNS
 
@@ -107,7 +147,6 @@ Azure-CLI features functionality for automatically maintaining this file for AKS
 Then apply one of the following manifests depending on whether you use RBAC or not.
 
 The credentials of the service principal are provided to ExternalDNS as environment-variables.
-At the end of this section, we additionally describe how to provide them as a _file_.
 
 ### Manifest (for clusters without RBAC enabled)
 ```yaml